Fix race condition in VC block proposal service (#1282)

Closes #918
Closes #923

common/rest_types/src/validator.rs

@@ -10,9 +10,10 @@ pub type ValidatorDutyBytes = ValidatorDutyBase<PublicKeyBytes>;
 /// A validator duty with the pubkey represented as a `PublicKey`.
 pub type ValidatorDuty = ValidatorDutyBase<PublicKey>;
 
+// NOTE: if you add or remove fields, please adjust `eq_ignoring_proposal_slots`
 #[derive(PartialEq, Debug, Serialize, Deserialize, Clone)]
 pub struct ValidatorDutyBase<T> {
-    /// The validator's BLS public key, uniquely identifying them. _48-bytes, hex encoded with 0x prefix, case insensitive._
+    /// The validator's BLS public key, uniquely identifying them.
     pub validator_pubkey: T,
     /// The validator's index in `state.validators`
     pub validator_index: Option<u64>,
@@ -25,7 +26,9 @@ pub struct ValidatorDutyBase<T> {
     /// The committee count at `attestation_slot`.
     pub committee_count_at_slot: Option<u64>,
     /// The slots in which a validator must propose a block (can be empty).
-    pub block_proposal_slots: Vec<Slot>,
+    ///
+    /// Should be set to `None` when duties are not yet known (before the current epoch).
+    pub block_proposal_slots: Option<Vec<Slot>>,
     /// This provides the modulo: `max(1, len(committee) // TARGET_AGGREGATORS_PER_COMMITTEE)`
     /// which allows the validator client to determine if this duty requires the validator to be
     /// aggregate attestations.
@@ -49,6 +52,20 @@ impl<T> ValidatorDutyBase<T> {
             false
         }
     }
+
+    /// Return `true` if these validator duties are equal, ignoring their `block_proposal_slots`.
+    pub fn eq_ignoring_proposal_slots(&self, other: &Self) -> bool
+    where
+        T: PartialEq,
+    {
+        self.validator_pubkey == other.validator_pubkey
+            && self.validator_index == other.validator_index
+            && self.attestation_slot == other.attestation_slot
+            && self.attestation_committee_index == other.attestation_committee_index
+            && self.attestation_committee_position == other.attestation_committee_position
+            && self.committee_count_at_slot == other.committee_count_at_slot
+            && self.aggregator_modulo == other.aggregator_modulo
+    }
 }
 
 #[derive(PartialEq, Debug, Serialize, Deserialize, Clone, Encode, Decode)]
@@ -74,3 +91,29 @@ pub struct ValidatorSubscription {
     /// for this slot.
     pub is_aggregator: bool,
 }
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn eq_ignoring_proposal_slots() {
+        let duty1 = ValidatorDuty {
+            validator_pubkey: PublicKey::default(),
+            validator_index: Some(10),
+            attestation_slot: Some(Slot::new(50)),
+            attestation_committee_index: Some(2),
+            attestation_committee_position: Some(6),
+            committee_count_at_slot: Some(4),
+            block_proposal_slots: None,
+            aggregator_modulo: Some(99),
+        };
+        let duty2 = ValidatorDuty {
+            block_proposal_slots: Some(vec![Slot::new(42), Slot::new(45)]),
+            ..duty1.clone()
+        };
+        assert_ne!(duty1, duty2);
+        assert!(duty1.eq_ignoring_proposal_slots(&duty2));
+        assert!(duty2.eq_ignoring_proposal_slots(&duty1));
+    }
+}